Group III-V compound semiconductors such as, for example, GaN and AlGaN are widely used for optoelectronics and electronics because of many advantages such as, for example, easily controllable wide band gap energy.
In particular, light emitting devices, such as light emitting diodes or laser diodes, which use group III-V or II-VI compound semiconductors, are capable of emitting visible and ultraviolet light of various colors such as red, green, and blue owing to development of device materials and thin film growth techniques. These light emitting devices are also capable of emitting white light with high luminous efficacy through use of a fluorescent substance or color combination and have several advantages of low power consumption, semi-permanent lifespan, fast response speed, safety, and environmental friendliness as compared to conventional light sources such as, for example, fluorescent lamps and incandescent lamps.
Accordingly, application sectors of the light emitting devices are expanded up to transmission modules of optical communication means, light emitting diode backlights to replace Cold Cathode Fluorescence Lamps (CCFLs) which serve as backlights of Liquid Crystal Display (LCD) apparatuses, white light emitting diode lighting apparatus to replace fluorescent lamps or incandescent lamps, vehicular headlamp, and traffic lights.
FIG. 1 is a view illustrating a conventional light emitting device package, and FIG. 2 is a view illustrating the shape of a solder in detail.
The conventional light emitting device package 100 includes a first lead frame 120a and a second lead frame 120b disposed on a sub-mount 110, and a light emitting device 140 is electrically coupled to the first lead frame 120a and the second lead frame 120b via solders 150a and 150b. 
The light emitting device 140 includes a substrate 141 and an underlying light emitting structure 142 including a first conductive semiconductor layer 142a, an active layer 142b, and a second conductive semiconductor layer 142c. The light emitting device 140 further includes a first electrode 144a disposed beneath one side of a lower surface of the first conductive semiconductor layer 142a and a second electrode 144b disposed beneath a lower surface of the second conductive semiconductor layer 142c, the first electrode 144a and the second electrode 144b being electrically connected to the first lead frame 120a and the second lead frame 120b respectively.
In the light emitting device package 100 as described above, the solders 150a and 150b are used for electrical connection between the light emitting device 140 and the first and second lead frames 120a and 120b. There may occur stress due to a difference between thermal expansion coefficients of different kinds of materials and, consequently, this stress may have a negative effect on the quality of the light emitting structure 142.
Since a height h01 of the light emitting device 140 is within a range of about 100 μm to 200 μM and a height h02 of the solders 150a and 150b is within about 30 μm, there is sufficient probability that the stress is transferred to the light emitting device 140 through the solders 150a and 150b. 
In addition, in a manufacturing process of the light emitting device package 100, after the solders 150a and 150b are applied to the respective lead frames 120a and 120b, the electrodes 144a and 144b of the light emitting device 140 are attached to the solders 150a and 150b. At this time, as exemplarily illustrated in FIG. 2, voids may be generated in an upper region of the solder 150b bonded to the second electrode 144b of the light emitting device 140.
The voids as described above may be generated while an interface between the solder 150b and the second electrode 144b is cooled in a heat treatment process for the solder 150b. Such void generation may result in defective electrical connection between the second lead frame 120b and the second electrode 144b of the light emitting device 140 or may prevent uniform light distribution throughout the light emitting device package 100.
In addition, the solder disposed between the electrode of the light emitting device and the lead frame may cause the light emitting device to deviate from a fixed position thereof during implementation of a reflow process. Moreover, when the solder is applied to a reflective layer disposed on the sub-mount to reflect light emitted from the light emitting device, light loss of the light emitting device package may occur.